The present invention relates generally to a spark unit for an internal combustion-powered fastener driving tool, and more particularly to a new and improved spark unit for an internal combustion-powered fastener driving tool wherein the unique and novel structure of the new and improved spark unit of the present invention effectively prevents the buildup and accumulation of dirt and oil such that the spark unit can be utilized for substantially longer periods of times without requiring maintenance and cleaning, and wherein further, quicker and more intense sparking of the unit is able to be achieved.
Combustion-powered fastener driving tools conventionally comprise a combustion chamber wherein a predetermined amount of combustible fuel is ignited within a combustion chamber so as to accordingly drive a piston which is operatively connected to a fastener drive blade or drive member. As the driver blade or driver member is driven, for example, downwardly by means of the piston, the driver blade or driver member will accordingly drive a fastener, disposed, for example, within a tool magazine containing a multiplicity of fasteners, into, for example, a suitable substrate.
A conventional internal combustion fastener driving tool is disclosed, for example, within U.S. Pat. No. 6,158,643 which issued to Phillips on Dec. 12, 2000. As can readily be seen in FIG. 1, which corresponds to FIG. 10 of the noted patent, a cylinder head is disclosed at 32, and a spark plug 40, which comprises a spark plug body 238 and a spark plug electrode 39, is mounted within the cylinder head 32. Spark plug body 238 has a spark plug O-ring 262, as well as a valve support 41, mounted thereon. Spark plug body 238 further defines an axial bore 240 which is arranged to house spark plug electrode 39 and which is also arranged to house a spark plug connector end portion of a piezoelectric conductor 224. An electrode 36, comprising a pin 202, is mounted upon an accelerator plate 33, and the electrode 36 and spark plug 40 are disposed opposite each other so as cooperate together and thereby define a spark gap 198 therebetween. It is further seen that the spark plug electrode 39 is actually mounted within the axial bore 240 of the spark plug body 238 in a recessed manner with respect to a front surface portion 237 of the spark plug body 238 such that an annular pocket or recess 239 is defined around the front tip portion of the spark plug electrode 39. While a combustion system such as, or similar to, the combustion system of the internal combustion fastener driving tool of Phillips usually operates quite satisfactorily, it has been experienced that over time, the disposition of the spark plug electrode 39 within the spark plug body 238, and in particular, within the recessed or pocket region 239, tends to result in the accumulation of dirt and/or oil within such recessed or pocket region 239 around the front tip portion of the spark plug electrode 39. Such an accumulation of dirt and oil can lead to difficulties in obtaining or achieving the proper and timely ignition of the spark plug electrode 39, and in addition, or alternatively, can require more frequent maintenance in order to maintain the recessed region 239 substantially free of oil and dirt.
A need therefore exists in the art for a new and improved spark unit or assembly for use within an internal combustion fastener-driving tool wherein the spark unit is mounted in such a manner that the spark unit electrode is not disposed within a recessed or pocket region and will in fact be disposed such that the free end or spark emitting tip portion of the spark unit electrode projects outwardly from the component within which the spark unit electrode is fixedly mounted such that oil and dirt is effectively prevented from accumulating around the spark unit electrode.
Accordingly, it is an object of the present invention to provide a new and improved spark unit or assembly for use within an internal combustion fastener-driving tool.
Another object of the present invention is to provide a new and improved spark unit or assembly for use within an internal combustion fastener-driving tool wherein the spark unit electrode is mounted in such a manner that operational disadvantages and drawbacks characteristic of PRIOR ART internal combustion fastener driving tool spark units or assemblies are effectively overcome.
An additional object of the present invention is to provide a new and improved spark unit or assembly for use within an internal combustion fastener-driving tool wherein the spark unit electrode is mounted in such a manner that the free end or spark emitting tip portion of the spark unit electrode projects outwardly from the component within which the spark unit electrode is fixedly mounted such that oil and dirt is effectively prevented from accumulating around the spark unit electrode.
A further object of the present invention is to provide a new and improved spark unit or assembly for use within an internal combustion fastener-driving tool wherein the spark unit electrode is mounted in such a manner that the free end or spark emitting tip portion of the spark unit electrode projects outwardly from the component within which the spark unit electrode is fixedly mounted such that oil and dirt is effectively prevented from accumulating around the spark unit electrode whereby improved spark ignition properties or characteristics of the tool are able to be achieved.
A last object of the present invention is to provide a new and improved spark unit or assembly for use within an internal combustion fastener-driving tool wherein the spark unit electrode is mounted in such a manner that the free end or spark emitting tip portion of the spark unit electrode projects outwardly from the component within which the spark unit electrode is fixedly mounted such that oil and dirt is effectively prevented from accumulating around the spark unit electrode whereby improved spark ignition properties or characteristics of the tool are able to be achieved while minimizing maintenance requirements.
The foregoing and other objectives are achieved in accordance with the teachings and principles of the present invention through the provision of a new and improved spark unit or assembly for use within an internal combustion fastener-driving tool wherein the spark unit electrode is fixedly mounted within the aluminum cast cylinder head such that the free end or spark emitting tip portion of the spark unit electrode projects outwardly from the outer surface of the cylinder head which defines one wall of the combustion chamber. In this manner, since the free end or spark emitting tip portion of the spark unit electrode is projects outwardly from the outer surface of the cylinder head and is not disposed within a recessed portion or pocket, oil and dirt is effectively prevented from accumulating around the spark unit electrode whereby improved spark ignition properties or characteristics of the tool are able to be achieved while minimizing maintenance requirements.